Help - haven't even seen a naked quadruple. I am not very good at finding hidden couples either. I would appreciate a few hints. Thanks.

If you did the March 17 Sudoku as suggested - Box 7 ended up like this:

5 123 6
479 8 13479
27 123 137

Quadruple in 123, 27, 123, 137
Therefore the numbers 1, 2, 3, & 7 will be used up in one or other of these cells.
Therefore you can eliminate these numbers from all other cells in this box.
Hope you understand this.

1 in r3c1 5 in r6c9 5 in r7c1 - Unique Horizontal
2 in r3c8 2 in r5c7 - Unique Horizontal
9 in r3c9 - Unique Horizontal
9 in r4c8 - Unique Vertical
6 in r4c9 - Unique in 3x3 block
4 in r4c7 - Unique in 3x3 block
3 in r5c8 - Unique in 3x3 block
6 in r6c5 - Unique Vertical
3 not in r1c6, it is in r3c4 or r3c5 (Row on 3x3 Block interaction)
4 not in r2c4, it is in r3c4 or r3c5 (Row on 3x3 Block interaction)
3 not in r6c4, it is in r4c4 or r4c5 or r4c6 (Row on 3x3 Block interaction)
3 not in r6c6, it is in r4c4 or r4c5 or r4c6 (Row on 3x3 Block interaction)
7 not in r8c4, it is in r7c5 or r7c6 (Row on 3x3 Block interaction)
7 not in r8c6, it is in r7c5 or r7c6 (Row on 3x3 Block interaction)
7 not in r9c4, it is in r7c5 or r7c6 (Row on 3x3 Block interaction)
1 not in r8c3, Hidden Pair 4 9 in r8c1 and r8c3 (in Row)
3 not in r8c3, Hidden Pair 4 9 in r8c1 and r8c3 (in Row)
7 not in r8c1, Hidden Pair 4 9 in r8c1 and r8c3 (in Row)
7 not in r8c3, Hidden Pair 4 9 in r8c1 and r8c3 (in Row)
1 not in r7c6, it is in r8c4 or r8c6 (Row on 3x3 Block interaction)
1 not in r9c4, it is in r8c4 or r8c6 (Row on 3x3 Block interaction)
7 not in r9c7, it is in r8c7 or r8c8 (Row on 3x3 Block interaction)
7 not in r9c8, it is in r8c7 or r8c8 (Row on 3x3 Block interaction)
1 not in r9c3, Hidden Pair 3 7 in r6c3 and r9c3 (in Column)
4 not in r6c3, Hidden Pair 3 7 in r6c3 and r9c3 (in Column)
9 not in r6c3, Hidden Pair 3 7 in r6c3 and r9c3 (in Column)
1 in r5c3 - Unique Vertical
8 in r4c1 8 in r5c5 - Unique in 3x3 block
4 in r6c4 - Unique in 3x3 block
4 in r3c5 4 in r5c2 2 in r6c6 2 in r9c4 - Unique in 3x3 block
3 in r3c4 2 in r7c2 - Unique in 3x3 block
2 in r1c1 1 in r9c2 1 in r7c9 - Unique in 3x3 block
3 in r9c3 3 in r8c7 - Unique in 3x3 block
3 in r1c9 3 in r6c2 7 in r9c1 7 in r8c8 - Unique in 3x3 block
4 in r2c9 7 in r6c3 9 in r6c1 9 in r8c3 6 in r9c8 - Unique in 3x3 block
4 in r1c3 9 in r2c2 4 in r8c1 5 in r9c7 - Unique in 3x3 block
6 in r1c2 8 in r2c3 5 in r1c8 8 in r1c7 8 in r9c9 - Unique in 3x3 block
5 in r2c6 7 in r2c7 - Unique in 3x3 block
6 in r2c4 7 in r1c6 6 in r8c6 7 in r7c5 - Unique in 3x3 block
7 in r4c4 1 in r8c4 3 in r7c6 - Unique in 3x3 block
1 in r4c6 3 in r4c5 - Unique in 3x3 block

Hello Kiwi,
17 mar needs only "hidden pair", can you see if I am right or wrong:
...
1 not in r8c3, Hidden Pair 4 9 in r8c1 and r8c3 (in Row)
3 not in r8c3, Hidden Pair 4 9 in r8c1 and r8c3 (in Row)
7 not in r8c1, Hidden Pair 4 9 in r8c1 and r8c3 (in Row)
7 not in r8c3, Hidden Pair 4 9 in r8c1 and r8c3 (in Row)
...
see u,

Kiwi wrote:

If you did the March 17 Sudoku as suggested - Box 7 ended up like this:

5 123 6
479 8 13479
27 123 137

You two are talking about the same thing and just using different terminology. The "hidden pair" is "revealed" by eliminating the elements of the "naked quadruple" from r8c1 and r8c3. So you're both right.

"What's in a name? A rose by any other name would smell as sweet." dcb

David - couldn't agree with you more. I think some of the explanations get much more complicated than they need to because of the terminology. Good to remember KISS principle ..... Keep It Simple Stupid!!